Compounds as textile softeners



United States Patent 3,442,695 COMPOUNDS AS TEXTILE SOFTE'NERS Lyle F.Elmquist, North St. Paul, Minn., assignor to General Mills, Inc., acorporation of Delaware No Drawing. Original application July 16, 1964,Ser. No. 383,256, now Patent No. 3,377,382, dated Apr. 9, 1968. Dividedand this application Oct. 13, 1967, Ser. No. 675 066 int. Cl. B32b33/00; C07c 83/00; Cm 7/30 US. Cl. 117139.5 6 Claims ABSTRACT OF THEDISCLOSURE Softened textile materials and the process of softeningtextiles which involves the application thereto of quaternary ammoniumcompounds in which two substituents on the nitrogen are derived from theresidual fatty acid monomer left after polymerization of higher fattyacids and the remaining two substituents are lower alkyl groups.

The present application is a division of application Ser. No. 383,256,filed July 16, 1964, now Patent No. 3,377,382, by Lyle F. Elmquist, forNew Compounds as Textile Softeners.

The present invention relates to certain novel fatty quaternary ammoniumcompounds and to their use for the softening of textiles.

A number of fatty quaternary ammonium compounds have been used in thepast for textile softening purposes. One very commonly in use at thepresent time is dimethyl difatty quaternary ammonium chloride, in whichthe fatty group is predominantly a C saturated group. These compoundsare generally made from a starting material rich in a C saturated fattyacid, particularly stearic acid, such as tallow. While these prior fattyquaternary ammonium compounds have been satisfactory insofar as theirsoftening properties are concerned, they have been subject to thedisadvantage that they have a water-proofing affect upon textilesthrough repeated use. Thus, for example, bath towels repeatedlysubjected to the use of the softening compounds have a reducedabsorbency and, therefore, are less desirable than towels having theoriginal absorbency.

It has now been discovered that it is possible to prepare fattyquaternary ammonium compounds which have approximately the samesoftening properties as the dimethyl dihydrogenated tallow quaternariescommonly employed at the present time, by preparing such quarternariesusing as a starting material the monomer fatty acid which is a residueleft after the polymerization of unsaturated fatty acids. Thesequaternary compounds have approximately the same softening properties asabove mentioned compounds but the rewetting characteristics are farsuperior.

The novel compounds from the present invention have the followingformula:

in which R and R are lower alkyl groups containing from 1 to 4 carbonatoms and R is the hydrocarbon radical corresponding to the residualfatty acid monomer left after the polymerization of higher unsaturatedfatty acids containing from 8 to 24 carbon atoms, and X is a quaternaryammonium anion. R and R may be methyl ethyl, propyl or butyl, eitherstraight or branched chain and preferably are both methyl. X may be anyconventional quaternary anion such as a chloride, sulfate, etho3,442,695 Patented May 6, 1969 sulfate, nitrate and the like. Because ofthe ease of preparation of compounds by methylation with methyl chloridethe chloride anion is preferred.

As was pointed out above, R is the hydrocarbon group derived from theresidual monomer from the polymerization of unsaturated higher fattyacids containing from 8 to 24 carbon atoms. Fatty acid polymers of atype referred to immediately above are articles of commerce. They havebeen prepared by the simple thermal polymerization of unsaturated fattyacids and also by the catalytic polymerization of such fatty acids, forexample by means of clay catalysts. In these polymerizations a mixtureof fatty acids containing from 8 to 24 carbon atoms usually derived fromnatural fat oil are employed as starting material. When these acids aresubjected either to a thermal polymerization for example at temperaturesof 260 to 300 C. or by catalytic thermal polymerization for example inthe presence of clay at temperatures from say 180 to 250 C., the fattyacids polymerize. In the thermal process the polyunsaturated fatty acidspolymerize most easily and the residual monomer is composed almostentirely of mono-unsaturated fatty acids together with any saturateswhich may have been present in the starting material. In the catalyticprocess both the polyunsaturated and the mono-unsaturated acidspolymerize and there is accordingly a lesser residue of monomer, butagain the unsaturated acids in the monomer are almost entirelymono-unsaturated. During the polymerization process the monomer, whileit does not polymerize, is modified in structure so that it no longerhas either the physical or chemical characteristics of the originalstarting material. In fact, it has been so modified that it usually nolonger finds use for the same purposes for which the fatty acid in itsunmodified form may be used. Consequently this residual monomer has inthe past found restricted use in commerce and in many instances wasburned as fuel since it had greater value for this purpose than for manyof conventional chemical uses to which it is adapted. Some concepts ofpossible structure for the residual monomer are to be found in theJournal of the Oil Chemists Society 26, No. 6, p. 278 (1949) andIndustrial and Engineering Chemistry, 44, 1113 (1952).

While it has been difficult to find suitable uses for this monomer inconventional applications, surprisingly enough when it is converted intoa fatty quaternary ammonium compound it possesses certain uniqueproperties which render it superior to materials produced from higherpriced raw materials. One such unique property involves the discoverythat the quaternary compounds have softening properties comparable toother commercially used compounds but have far superior rewettingcharacteristics as will be demonstrated in further detail hereinafter.

In preparing quaternary ammonium compounds from the residual monomer themonomer is converted to the nitrile by reaction with ammonia in theconventional manner. The nitrile thus obtained is then hydrogenated inthe presence of a catalyst to produce a secondary fatty amine, (R NH.The production of the secondary amine is carried out in a manner wellunderstood in the art. The secondary amine is then converted to thequaternary ammonium compound by the reaction with typical alkylatingagents such as methylchloride. Again the alkylation reaction is wellknown in the prior art and forms no part of the present invention.

The residual monomer starting material contains an appreciable amount offatty acids still possessing some residual unsaturation. In general,quaternary ammonium compounds prepared from this residual monomer haveexcellent softening properties and excellent rewetting properties.However, if the fatty group in the quaternary compound possessessubstantial unsaturation, there is a tendency for the textile materialssoftened with these compounds to take on a yellow cast which isgenerally considered undesirable. This tendency toward yellowing doesnot interfere with the softening properties but merely raises someaesthetic objections; accordingly, it is preferred to reduce the amountof unsaturation in the fatty group so the resultant quaternary compoundhas an iodine number of 40 or less. This may be accomplised by suitablyhydrogenating the monomer starting material or it may be accomplished bythe hydrogenation conditions encountered in forming the amine from thenitrile. While it is possible to reduce the iodine value byhydrogenation, it is extremely difficult to get an iodine numberapproaching zero. Apparently, to some extent, the nature of theunsaturation has been modified during the polymerization process so thatnot all double bonds may be saturated with hydrogen. It is possible,however, to hydrogenate the iodine value below 40 and indeed it may bepossible to reduce the iodine value to 5 or less. These hydrogenatedproducts are superior with reference to any yellowing tendencies.

In the preparation of a textile softening material from the quaternarycompound, the quaternary is usually dispersed in an aqueous mediumeither by itself or with the assistance of an organic solvent, such as alower aliphatic alcohol, for example, isopropanol. As a convenientmanner of distributing the softener on the textile surface, thesoftening agent may be used in a concentration of the order of magnitudeof 0.007 07% by weight of the solution. conventionally these are used atlevels of approximately 0.00125 gram of softening compounds per gram ofdry textiles. The amount of softener used can vary considerably butgenerally is within the range of 0.0005 to 0.005 gram per gram of drytextile.

The softening ability of the various compounds was determined in thefollowing test: Swatches of white birdseye cotton (36" x 12') are placedin a normal 8-pound wash load and are washed at 140 F. with aconventional household detergent in the same manner as is done in aregular household wash. The swatches are washed in an automatic washerwith a 6-minute wash cycle followed by a 1-minute spray rinse and a4-minute final deep rinse. The swatches are then dipped in solutions ofthe compound being tested.

The dipping is done in a water bath using beakers and agitation isprovided by means of a stirring rod. The dipping is carried outduplicating the conditions in the last rinse of the automatic washmachine which are: 4 minutes of agitation at 100 F. using a 0.00707%solids solution concentration (for normal use level) and a 17.7 to 1solution to dry fabric ratio. This results in a normal use level of0.00125 gram per gram of dry fabric. The swatches are allowed to stand 1minute following agitation and the dipping solution is then poured offand the swatches are spun in the washer to remove excess dippingsolution. The swatches are then allowed to air dry before being cut upfor testing. After drying, each swatch is cut into twelve samples (4" x4"). The samples are marked and placed in a room under controlledtemperature and relative humidity until tested (50 relative humidity at72 F.).

The panel testing is carried out by panel of twelve women who test induplicatemaking a total of twentyfour tests. Each test consists ofcomparing the softness of three pairs of samples. These pairs have beentreated as follows:

(1) One and one-half normal use level test compound vs. normal use levelof the standard compound,

(2) Normal use level test compound vs. normal use level of the standardcompound and (3) Normal use level test compound vs. one half normal uselevel of the standard compound. The panel is asked to indicate whichsample of each pair they think is the softer. The results are treatedstatistically using the method of X (Chi-squared) where (o=observed, eexpected).

Reference: Applied General Statistics by Croxton and Cowden, (copyright1939, by Prentice-Hall, Inc.) The value of X is then looked up in asignificance table to see if the results are significant and if so, atwhat level of significance. From these results it is possible todetermine if the compound is as good as the standard compound, one-halfas good as the standard compound or somewhere in between one-half asgood and as good as the standard compound in softening efficiency.

By the above test, it was determined that the compounds of the presentinvention were approximately equal in softening ability to the standardcompound used for comparison.

The rewetting characteristics were determined as follows: Swatches ofbirdseye cotton (24" x 12") are washed in an automatic washer, using theconventional household detergent but are removed before the final deeprinse. Two swatches are dipped in a normal concentration solution of thestandard compound and two swatches are dipped in twice the normalconcentration of the compound being tested. The dipping procedure is thesame as used in the above-described softener test. One of the swatchesdipped in the normal concentration of the standard compound and one ofthe swatches dipped in twice the normal concentration of the testcompound are then put through an identical wash-soft cycle so that therewettting test is run on samples dipped in normal and twice the normalsoftener use levels, both after one and after two wash-soften cycles.After dipping, the swatches are air dried and each swatch cut into two10" x 10" samples. The samples are marked and placed in a room undercontrolled temperature and relative humidity (50% relative humidity at72 F.) for conditioning. Testing was carried out under these temperatureand humidity conditions.

The rewetting test consists of dropping drops of water on a sample oftreated cloth from a buret and determining the average length of time ittakes for the drops to soak into the cloth. The buret is held about inchfrom the sample and is adjusted so that it delivers approximately onedrop of water every five seconds. The sample is held over a six-inchmetal framework so that all parts of the cloth are under equal tension.The sample was held taut over the framework by means of a 137 gramweight clipped to each side of the sample by six-inch jaws. A drop ofwater is dropped on the cloth and the time taken for the disappearanceof this drop is taken as the rewetting time. Ten such tests are run oneach sample, making a total of twenty tests for the two samples. Theaverage rewetting time is then the average of these twenty tests.

Example Tall oil fatty acids were heated at atmospheric pressure in thepresence of 10% montmorillonite clay at a temperature of 200-230 C. for4 hours. The reaction mixture was then filtered to remove the clay andthe filtrate was subjected to vacuum distillation to remove the residualmonomer.

This monomer was then converted to the nitrile by heating it in a potreactor at a temperature of 250-300 C. for a period of 5-10 hours whileblowing ammonia through the reaction mixture. The reaction isessentially complete when the acid value is reduced to less than one andthe amide content is below 2%. At this point, the reaction mixture issubjected to vacuum distillation to remove the nitrile.

The nitrile is converted to the secondary amine by hydrogenating it withRaney nickel at 200 pounds per square inch pressure at a temperature ofaround 225 C. while periodically removing ammonia formed during thereaction. Upon completion of the reaction, the reaction mixture wascooled to about 100 C. and then filtered to yield a product having atotal amine content of 99.0%, a secondary and tertiary amine content of93.3 and a tertiary amine content of 3.7%

During the course of the hydrogenation, the iodine value was reduced to12.3.

This sceondary amine was then quatemized with methylchloride in thepresence of isopropanol and alkali. The reaction was conducted at 70 to80 C. for a period of about 15 hours after which the product was cooledand filtered to yield a product which was 69.1% solids and whichcontained 68.0% quaternary.

This quaternary was then dispersed in water to yield a solutioncontaining 0.00707% solids and this solution was used to treat fabricsas described above. As indicated, the product had essentially equalsoftening characteristics but decidedly improved rewettingcharacteristics. The compound showed rewetting times in the general areaof 5 to 18 seconds as compared with rewetting times in the general areaof 100 to 300 seconds for the standard used for comparison, which was adimethyl dihydrogenated tallow ammonium chloride which is used in largevolume in current clothes softeners.

Similar results were obtained with the quaternary ammonium chlorideproduced from residual monomer from the thermal polymerization of fattyacids.

While specific examples of the invention have been described, it will beevident that other variations of the invention are opssible within thescope of the following claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. Process of softening textiles which comprises distributing on thesurface of the fibers a compound having the formula Rs RfiI IRQ 1'1. inwhich R and R are lower alkyl groups containing from 1 to 4 carbon atomsand R is the hydrocarbon radical corresponding to the residual fattyacid monomer left after the polymerization of higher unsaturated fattyacids containing from 8 to 24 carbon atoms, and X is a quaternaryammonium anion.

2. Process according to claim 1 in which R and R are methyl, and X ischlorine.

3. Process according to claim 2 in which said compound is present withinthe range of 0.0005 to 0.005 gram per gram of dry textile.

4. Textile material having deposited on the surface of the fibersthereof a softening amount of a compound having the formula in which Rand R are lower alkyl groups containing from 1 to 4 carbon atoms and Ris the hydrocarbon radical corresponding to the residual fatty acidmonomer left after the polymerization of higher unsaturated fatty acidscontaining from 8 to 24 carbon atoms, and X is a quaternary ammoniumanion.

5. A textile material according to claim 4 in which R and R are methyl,and X is chlorine.

6. Textile material according to claim 5 in which said compound ispresent on the textile in the range of from 0.0005 to 0.005 gram pergram of dry textile.

References Cited UNITED STATES PATENTS 3,073,864 1/1963 Harrison260567.6 3,122,502 2/1964 Waldman et al. 2528.8 3,175,008 3/ 1965Shapiro et a1 260567.6 3,395,100 7/1968 Fisher et al. 2528.8

HERBERT B. GUYNN, Primary Examiner.

US. Cl. X.R.

